the 3GM needs a lot of fuel right away in cold weather. my yanmarmechanic said to give it full throttle but i found 60 was enough. i also found that if it does not start right away it is better to stop and try again in a few minutes. too bad the yanmar folks did not give it the glow plugs that would have fixed this issue.

Well there you go and there you have it...
Problem solved.
Sailboats do not belong in cold weather!!

the 3GM needs a lot of fuel right away in cold weather. my yanmar mechanic said to give it full throttle but i found 60 was enough. i also found that if it does not start right away it is better to stop and try again in a few minutes. too bad the yanmar folks did not give it the glow plugs that would have fixed this issue.

Worked on quite a few of those yanmars on the farm and on boats. I would check the following in this order;
Fuel rail tubes, are they porous? Any dampness.
Fuel injectors. Should be rebuilt or cleaned every 750 hours. I know I know no one does.. Usually only 50 to 75 bucks to get done if u are in the states.Lift pump

Worked on quite a few of those yanmars on the farm and on boats. I would check the following in this order;
Fuel rail tubes, are they porous? Any dampness.
Fuel injectors. Should be rebuilt or cleaned every 750 hours. I know I know no one does.. Usually only 50 to 75 bucks to get done if u are in the states.Lift pump

Well pulled the injectors out today and cleaned the light carbon buildup around the injector nozzle today. The carbon just wiped off with a soft rag. Put new O-rings around each injector. Yanmar uses O-rings in the GM's it seems.

Alas no real difference. Though throttle response and engine sounds a little better.

I had pulled and checked the lift pump a few days ago and it was fine, pumped fine with lever or cam arm and no back leak through the valves.

So, I've decided for the moment to do the blonde thing and let it go, unless it gets a lot worst. Once started the engine runs fine, though it has excessive crankcase pressure, I just ran the crankcase vent to the air cleaner intake, So pressure will not build up and leak oil out the valve cover.

That BTW was why I first started down this path, as the engine was leaking oil out from around the valve cover nuts. Took the breather hose off and it was like letting air out if a tire. I did check both ends of the breather and all is clear now. I think the 1/16" ish hole in the manifold was clogged. But it still will build up pressure and leak oil... With the breather hose run to the air cleaner the oil leaking stops. I do get a mist out of the breather, so betting I have a slight ring issue. But was in denial for a while there

So betting either I have a broken ring, glazed cylinder wall or possibly a blow headgasket to the oil galleys.

So as long as it starts ok, That is it does not get much worst and runs fine I'm just going to ignore the problem and just watch my oil consumption...

Well pulled the injectors out today and cleaned the light carbon buildup around the injector nozzle today. The carbon just wiped off with a soft rag. Put new O-rings around each injector. Yanmar uses O-rings in the GM's it seems.

Alas no real difference. Though throttle response and engine sounds a little better.

I had pulled and checked the lift pump a few days ago and it was fine, pumped fine with lever or cam arm and no back leak through the valves.

So, I've decided for the moment to do the blonde thing and let it go, unless it gets a lot worst. Once started the engine runs fine, though it has excessive crankcase pressure, I just ran the crankcase vent to the air cleaner intake, So pressure will not build up and leak oil out the valve cover.

That BTW was why I first started down this path, as the engine was leaking oil out from around the valve cover nuts. Took the breather hose off and it was like letting air out if a tire. I did check both ends of the breather and all is clear now. I think the 1/16" ish hole in the manifold was clogged. But it still will build up pressure and leak oil... With the breather hose run to the air cleaner the oil leaking stops. I do get a mist out of the breather, so betting I have a slight ring issue. But was in denial for a while there

So betting either I have a broken ring, glazed cylinder wall or possibly a blow headgasket to the oil galleys.

So as long as it starts ok, That is it does not get much worst and runs fine I'm just going to ignore the problem and just watch my oil consumption...

Well sailorchic I'm not blonde and I would probably do the same:-). I would at one point have the injectors rebuilt. One last thought and then back to my hammock, do you have glow plugs on each cylinders?

Well sailorchic I'm not blonde and I would probably do the same:-). I would at one point have the injectors rebuilt. One last thought and then back to my hammock, do you have glow plugs on each cylinders?

no glow plugs. The yanmar gm series engine are straight compression engines...

You could have a pop test done on the injectors. I had a 4 cyl Perkins that seemed to run fine, but was getting fuel in the oil. Turned out to be a bad injecter that was flooding the cylinder on one cylinder. The test found it right away.

__________________"I spent most of my money on Booze, Broads and Boats. The rest I wasted" - Elmore Leonard

Well pulled the injectors out today and cleaned the light carbon buildup around the injector nozzle today. The carbon just wiped off with a soft rag. Put new O-rings around each injector. Yanmar uses O-rings in the GM's it seems.

Alas no real difference. Though throttle response and engine sounds a little better.

I had pulled and checked the lift pump a few days ago and it was fine, pumped fine with lever or cam arm and no back leak through the valves.

So, I've decided for the moment to do the blonde thing and let it go, unless it gets a lot worst. Once started the engine runs fine, though it has excessive crankcase pressure, I just ran the crankcase vent to the air cleaner intake, So pressure will not build up and leak oil out the valve cover.

That BTW was why I first started down this path, as the engine was leaking oil out from around the valve cover nuts. Took the breather hose off and it was like letting air out if a tire. I did check both ends of the breather and all is clear now. I think the 1/16" ish hole in the manifold was clogged. But it still will build up pressure and leak oil... With the breather hose run to the air cleaner the oil leaking stops. I do get a mist out of the breather, so betting I have a slight ring issue. But was in denial for a while there

So betting either I have a broken ring, glazed cylinder wall or possibly a blow head gasket to the oil galleys.

So as long as it starts ok, That is it does not get much worst and runs fine I'm just going to ignore the problem and just watch my oil consumption...

Have a diesel injector shop check them, they'll tear them down and clean them. I had 'varnished' injectors and listened to the sermon about running the engine for 20 minutes at least once a week. Of course this led to having the injector pump go through the same process. That was at ~700 hours, now 2000 and engine still runs like new. Yes, diesel will varnish like gasoline.

FWIW, the governor holds the fuel rack at WOT with the engine off so you get full fuel while cranking.

Well its been a while, and my yanmar 3gm30F still is hard starting hot or cold. Plus it has high maybe very high crankcase pressure. Enough that oil is being pumped to the intake manifold. Currently using a pint every 5 hours or so. Lovely.

In talking to a serious car and boat nut, he seems to think its a bad ring or two.

When the engine is running, pulling the decompression on each cylinder, shows similar drop across all three cylinders. Once running, it runs fine and does not smoke. It is running about 5-10 degrees warmer at about 175-180 degrees F. Use to always run at about 170 degrees F. But that could be caused by the extra oil going in the intake. It also seems to warm up much faster.

No oil in coolant and no water in the oil. Lift pump is fine. I have checked and adjusted the valves, bleed and checked for a vacuum leak, etc. etc.

To start it I pretty much have to crank for 5-10 seconds at 50 % throttle, stop and wait 20-30 seconds and then crank it again at 30%. Then it will start. Well it will fire on one cylinder but then dies when the start button is released. This even in 80 degree weather, or 40 degree weather. It does not fire at all about 30 percent throttle.

Hot or cold it is hard starting. Even if I stop the engine and try to restart it right away, its very hard to start. Acts exactly the same way.

I get light grey smoke out the exhaust when it first starts and the smoke stops one all three cylinders are firing. One fires right away, second in 2-5 seconds and third at about 10 seconds.

I have not changed the injectors yet. But with the high crankcase pressure, IE it looks like exhaust out the oil fill at idle (not a good thing), I'm thinking its not the injectors but then I not sure. At the moment I'm thinking its rings or if I'm really lucky a head gasket blow out at the oil galleys. Engine once completely warmed up runs fine, though it did die on me once when I put it in gear at idle after it was warmed up. Hum.

Engine will run at 3100 rpm at wot, but not any higher. No smoking then either. I normally run at 2100-2200 rpm.

So I'm looking for that magic bullet or something, OK anything other then rings, like the feingle nut being loose or some such. Could the injectors being bad cause very high crankcase pressure and oil use??

At the moment I'm just living with it as the weather is too nice to be stuck messing with an engine. Guess that's the blonde in me.

Sheesh, SC, but that surely does sound like low compression due to leaky rings. Bad injectors would not explain high crankcase pressure nor would a head gasket leak. Could also possibly be glazed bores causing the blowby...

So, once the weather breaks for the worse, you maybe will want to pull the injectors and actually measure the compression. then when the truth is revealed, consider how to renew the rings and/or run a glazebuster hone in the bores. A fair amount of disassembly is required. I'm not personally familiar with your engine... when I had to do a similar operation on a BMW D-35, I found that the head came off and then so did the cylinder block. Thus I was able to leave the bottom end intact and in the boat whilst I did the bores and rings. Just how difficult this might be depends a lot an access to the engine. Fairly easy o n our old race boat, not always the case in others!!

Sure hope that you can find a reasonable means of doing it, 'cause it sure sounds like it is on your to do list!

Other than head gasket as you mentioned, the only other suspect I can think of would be a combination of pitted valves and seats (causing poor starting) and worn valve guides aka bushes (causing crankcase pressurisation)

I don't think this is a likely explanation, but unlikely things happen every day, to someone... so it's worth eliminating

A bit of grayish white smoke on start up could point to a poor injector. The seat between the injector tip and needle can and will wear or the spring is weak. This could allow a small amount of raw fuel to leak into the cylinder as well as air to find its way into the injector. This will give hard starting and the smoke on start up. Like someone already stated. All mechanical/electric governed diesels are at wide open throttle for stat up.

I'm hoping its the head gasket or a bad valve or two. I have a spare head gasket, but sort of waiting till I know if its the head gasket or not.

Removing the head is so much easier then pulling the engine. Though still not on my fun list. I do get a little whistling after it first starts, very light and goes away above idle or once warm. Or at least my half deaf ears can't hear it anyway.

Glazed bores is a possiblity. Going to try some seafoam to see if that helps or not. I've heard that helping one fella. I did put some cetane boost in the tank, but that did not seem to really help.

With only a 1000 hours in the engine, I was/am hoping its not rings. Looks like I'll be having a delightful fall/winter.